Snap action devices



May 10, 1960 HUGHEY 2,936,350

SNAP ACTION DEVICES Filed Dec. 2'7, 195'? F/G' Z 9 a; 24 :2; 6 2,2 2e 7 [Hole I3 25 INVENTOR Orv/6H7 M H 15 y ATTORNEY Unite rates Patent SNAP ACTION DEVICES Application December 27, 1957, Serial No. 705,686

7 Claims. (Cl. 200-67) This invention relates to devices wherein the motion of a slowly moving actuating means is converted to snap action of a movable element to be actuated. While not limited thereto, the invention is particularly applicable to snap acting electrical switches.

The broad object of the invention is to provide a simple and dependable means for imparting snap actuation to a movable element, the snap actuation being independent of the rate of movement of the operating means employed to initiate such actuation.

Another object is to devise a snap switch wherein the operating means can be allowed a relatively large travel while movement of the movable contact elements of the switch occurs instantaneously at a given point in the travel of the actuator in such fashion as to assure truly instantaneous making and breaking of the switch contact.

A further' object is to provide such a switch wherein the contacts are held engaged with a contact pressure, which pressure is never less than a desired amount prior to the instant of breaking of the contacts. The contact pressure is maintained at a particular level prior to disengagement of the contacts, such level being independent of the rate and amount of displacement of the actuating means until breaking of the contacts occurs. In this connection, switches constructed in accordance with the invention have higher contact ratings, longer contact life and greater freedom from the effects of shock and vibration than is the case with conventional switches.

Yet another object is to provide such a switch embodying two cooperating resilient means, one-operating to maintain a desired contact pressure, and the other operating first to add to such contact pressure and then to accomplish instantaneous disengagement of the contacts.

In order that the manner in which these and other objects are attained in accordance with the invention can be readily understood, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

Fig. 1 is a plan view of a switch constructed in accordance with one embodiment of the invention, the switch being illustrated without its housing, cover plate and operating rod for clarity;

Fig. 2 is a vertical sectional view taken on the line 2 2, Fig. 1; r

Fig. 3 is a vertical sectional view taken on the line 3-3, Fig. 1, with some parts shown in elevation and illustrating the operating rod and cover plate;

Fig. 4 is a view in perspective, on an enlarged scale, illustrating the movable contact assembly of the switch shown in Fig. 1;

Fig. 5 is a fragmentary elevational view, on an enlarged scale, of the operating means of the switch of Fig. 1, and

Figs. 6-8 are schematic views, on an enlarged scale relative to Fig. 1, illustrating one operating sequence of this embodiment of the invention. Referring now to the drawings in detail, it will beseen Patented May 10, 1960 ice that the embodiment of the invention here illustrated comprises a base 1 of insulating material provided with integral corner posts '2. The base 1 has a generally square plan shape. At two opposite sides of the square, the base 1 is provided with a first set of fixed contact posts 3 and a second set of shorter fixed contact posts 4. At one of the remaining sides of the base, there is provided an additional post 5 which, as will be explained, is employed to support a flexible operating member. At the remaining side of the base, there is provided a fixed abutment member 6.

Secured to post 5 is one end of a flexible member 7 provided with a longitudinal slot 8. Located above member 7, and also supported on post 5, is an upper stop member 9 which, for most of its length, comprises two spaced arms disposed one on each side of the slot 8. As best seen in Fig. 2, the free ends of the arms of stop member 9 are turned downwardly to provide stop surfaces lying in a plane parallel to but spaced above base 1, these stop surfaces being disposed for engagement by the member 7 when the same is moved away from the base. At a point below these stop surfaces, the base 1 carries a lower stop bar 10 to be engaged by the memher 7 during its movement toward the base. The members 7 and 9 are secured to post 5 in any suitable fashion, as by the screw 11, Fig. 2.

Each post 3 mounts, as by a screw, a fixed contact arm 12, the arms 12 being provided with downwardly directed fixed contacts at their free tips. Each of the posts 4 similarly mounts a fixed contact arm 13, the arms 13 carrying at their free ends upwardly directed fixed contact elements. As best seen in Fig. 3, the fixed contact arms 13 are disposed relatively close to base 1, while the fixed contact arms 12 are spaced well thereabove, so that the fixed contacts at the tips of the arms 12 and 13 are spaced apart in a direction at right angles to base 1 and therefore generally in the direction of travel ofthe tip of flexible member 7.

Two flexible contact arms 14 are provided one at each side of member 7, the arms 14 being secured in any suitable manner, as by a screw, at one end to the base 1 adjacent post 5 and at their other ends to a movable contact carrier 15, seen in detail in Fig. 4. Each arm 14 is secured to movable contact carrier 15 by a rivet 16, the ends of each rivet 16 providing opposed movable contact elements, as will be clear from Fig. 3. Thus, the connection for each arm 14 provides a contact facing upwardly from the element 15 and a' contact facing downwardly therefrom, these contacts being operatively disposed with reference to the fixed contacts carried by arms 12 and 13. i

The contact carrier 15 is generally diamond-shaped in plan, having spaced central portions 15 and 15 and outwardly converging arms 15 extending from said central portions to the arms 14. Secured to the central portions of member .15, as by rivets 17, and extending therebetween parallel to arms 14, is a relatively rigid sheet metal member 18, the transverse cross-section of which has the shape of an inverted U. Between portions 15 and 15 of member 15, portions of the base web of member 18 are cut away, so that the member 18 is provided with a centrally located cross bar 19 having integral cars 20 and 21 extending in the direction of member 7.

Disposed between the cross bar 19 of member 18 and the fixed abutment member 6, and extending above portion 15 of member 15 without contacting the same, is a first bow spring 22. The spring 22 is provided with openings at its tips, one such opening being engaged over car 20, so that that end of the bow spring is fulcrumed on the member 18 and thus on the movable contact assembly. The opening at the other end of how spring 22 receives a projection 23 formed integrally with mem- 3 her 6 as best seen in Fig. 2. Thus, this end of bow spring 22 is fulcrumed on member 6. The projection 23 is disposed midway between the fixed contacts carried by arms 12' and 13. i

Disposed betweenportion 19 ofmember .18 and the tip of member 7, and extending above portion 15 :of member 15, without contacting said portion, is a second bow spring 24 which, like spring 22, is provided with openings at its ends. The opening at one end of spring 24 is engaged over car 21 ofcross bar 19, while the opening at the other end of the spring is engaged over a projection25 at the free end of spring element 7.

The bow springs '22, v24 are always compressed, since the distance between the points at which the tips of bow springs 22, 24 are engaged is always less than the distance between the tips of each such spring prior to positioning of the spring in the switch.

Pivotal movement of flexible member 7, between the stop surfaces provided by members 9 and 10, is initiated by means of an operating rod 26. Rod 26 extends genorally at right angles to base 1 and has, intermediate its ends, aportion -27 of reduced diameter engaged in the slot 8 in'member 7. As best seen in Fig. 5, presence of the :portion 27 provides a lower shoulder 27 of a diameter larger than the width of slot 8, and an upper shoulder 27 of like diameter. Upward movement of rod 26 brings shoulder 27 into engagement with the lower side of member 7, while downward movement of the rod brings shoulder 27 into engagement with the :top side of member 7. Adjacent post 5, slot 8 communicates with .a circular opening of suflicient diameter to accommodate the normal diameter of the rod 26, allowingithe rod to be inserted between the two spaced arms of upper stop member 9 and through the circular opening in member '7 until the portion 27 thereof of the rod reaches slot 8, at which point the actuating rod can bemoved laterally to obtain the relation seen in Fig. 5.

Supported by corner posts 2 is a cover plate 29, Fig. 3,1of insulating material and having an opening through which operating rod 26 extends. Above the plate 29, the rod 26 carries a head 30 larger in diameter than the rod, and a coil spring 31 is disposed between plate 29 and head 30 concentrically about the rod.

Operation of the switch will be clear from Figs. 6-8. The normal positions of the moving parts of the switch .are.illustrated diagrammatically in Fig. 6, member 7 being in engagement with stop member 9 and carrier 15 being in its lowermost position with its contacts engaging :the fixed contacts supported by arms 13. The lower shoulder 27 of rod 26 engages the bottom surface of :member 7 because of the biasing action of spring 31.

At rod 26 descends toward base 1, the upper shoulder 27 'contacts the upper surface of member 7, urging the same toward base 1. As the free end of member 7 approaches a position in which it is aligned with ear 23 of fixed abutment member 6, how springs 22 and 24 continue to resiliently urge member 15 toward base 1. There is accordingly no relative movement between the electrical contacts of the switch at this time. However, as

.member 7 approaches the position shown in Fig. 7, bow :spring 24' is pivoted about its fulcrum on cross bar 19, "until the force applied resiliently by that spring is ditrected parallel to base 1. Throughout this movement,

the contact pressure applied by bow spring 22 remains unchanged. Any further movement of member 7 to ward base 1 now causes spring 24 to urge member '15 away from the base. As has been noted, the projection 23 of fixed fulcrum member 6 is disposed midway between the fixed contacts carried by arm 12 and the fixed contacts carried by arm 13. Thus, when element 7 is in any position between those shown in Figs. 6 and 7, .spring 22 acts resiliently to maintain contact engage- .ment.

However, as element 7 moves further toward base 1, a spring force is built up in spring 24 in opposition to that presented by spring 22. The spring force .ofspring 24 predominates, as the movement of element 7 proceeds, the member 15 then being urged upwandly, causing the contacts '16 of member 15 to break contact with the contacts carried by arms 13 substantially instantaneously. The upward movement of member -15 continues until the contacts carried thereby engage the contacts carried by arms 12.

At the time the force of spring 24 predominates, the lower shoulder 27* of actuating rod 26 is approximately in..line with the top surface of lower stop bar 10. "This permits free movement of the free end of member 7, due to the force exerted by spring 24, from the upper shoulder 27 to the lower shoulder 27 This freedom of movement makes the movement of member 15 and contacts 16 away from the contacts of arms 13 completely independent of the rate at which the rod 26 is displaced in the direction of base 1. Such independence is especially importantwhen rod 26 is being moved slowly. When the force applied to rod 26 directingit toward base :1 is sufliciently reduced, oriremoved, spring 31 returns operating rod 26 to its normal position. As the rod 26 is thus moved away from base 1, lower shoulder 27*- engages member 7 and pivots the same upwardly. .Withthe free tip of member 7 now moving upwardly, the switching action explained above is reversed, resulting in movement of carrier 15 downwardly until its contacts again engage those carried by arms 13.

It will be understood that the operating force can be applied to rod 26 manually or by any suitable power device.

I claim:

7 1. In a snap switch, the combination of stationary means presenting a fulcrum portion, movable means. presenting a fulcrum portion directed toward and spaced from said stationary fulcrum portion, two fixed contacts spaced generallyin the direction of movement of said movable fulcrum portion, movable contact means disposed to cooperate with said fixed contacts, a first resilient means operatively connected to said movable contact means to bias said movable contact means against either of said fixed contacts, and a second resilient means operatively connected to said movable contact means to move the same substantially instantaneously from engagement with one fixed contact to engagement with the other, said first resilient means comprising a bow spring having its .ends 'fulcrumed respectively on said stationary fulcrum portion and said movable contact means, and said second resilient means comprising another bow spring having its ends fulcrumed respectively on said movable fulcrum portion and said movable contact means.

2. In a snap switch, the combination of stationary meansproviding a fixed fulcrum portion; movable means ,presenting .a'fulcrum portion directed toward and spaced ..from said fixed fulcrum portion; two fixed contacts spaced .apart in thedirection of travel of said movable fulcrum portion; a movable contact carrier disposed for move- .ment betwen said fixed contacts and provided with contacts operatively disposed with respect to said fixed contacts; two bow springs generally aligned across said carrier, one of said springs having its ends fulcrumed respectively on said carrier and said movable fulcrum portion and being elfective to move said carrier substantially in stantaneously from engagement with one of said fixed con tacts to engagement with theother, the other of said springs having its ends fulcrumed respectively on said fixed fulcrum portion and said carrier, said other spring being of such length as to be held in compression throughout the movement of said carrier and being eifective to tbiastsaid carrier against either of said fixed contacts; and

means operatively connected to said movable means to move the same in said direction of travel, said movable .xfulcrum portion being substantially free to move with the corresponding end of said between said fixed contacts. I

--3. snap switch inaccordancewith claim 2 and-whereone spring when midway ansaseo in said means for moving said movable means includes a lost motion connection.

4. In a snap switch, a pair of fixed contacts, a movable contact carrier disposed for movement between said fixed contacts and provided with contacts operatively disposed with respect to said fixed contacts, a fixed member presenting a fixed fulcrum portion disposed substantially midway between said fixed contacts and spaced from said carrier, a compression spring extending between said fixed fulcrum portion and said carrier and having its ends fulcrumed respectively thereon, a bow spring aligned generally across said carrier from said compression spring and having one end fulcrumed on said carrier, and movable means comprising a fulcrum member disposed for movement generally in the direction of travel of said carrier and spaced therefrom on the side opposite said fixed member, said movable means also including means selectively engageable with said fulcrum member to move the same toward one or the other of said fixed contacts, the other end of said bow spring being fulcrumed on said fulcrum member, said bow spring being operative to move said carrier in snap fashion through its full travel between said fixed contacts in either direction in response to movement of said fulcrum member and said compression spring being operative to bias said carrier against either of said fixed contacts.

5. In a snap action device, the combination of a memher to be actuated between two extreme positions; controlling means carried by said member; spaced stop means mounted for engagement by said member to stop the same in said positions; two bow springs generally aligned end-to-end on opposite sides of said member, the adjacent ends of said springs being fulcrumed on said member; stationary means spaced laterally from said member and disposed approximately midway between said spaced stop means, the other end of one of said springs being fulerumed on said stationary means, operating means spaced from said member on the side thereof opposite said stationary means, the other end of the other of said springs being fulcrumed on said operating means and said operating means being mounted for movement generally in the plane of the bows of said springs, and other spaced stop means disposed to limit such movement of said operating means, the effective spacing between said other stop means being greater than the effective spacing between said firstmentioned stop means, the midpoint of the travel of said operating means being substantially aligned with said stationary means and the midpoint of the travel of said member.

6. In a snap action device of the type embodying a movable component to be actuated with snap action from one operative position to a second position and thence back to said first position, the combination with such component of controlling means carried by said component; spaced stop means disposed for engagement by said component in said positions, actuating means comprising fixed fulcrum means and movable fulcrum means spaced across said movable component, said fixed fulcrum means being generally centered between said positions and said movable fulcrum means being mounted for movement generally in the direction of travel of said movable component, second spaced stop means operatively associated with said movable fulcrum means and disposed to confine the movement thereof to a distance centered on said fixed fulcrum means, said distance being such that said 5 movable fulcrum means is allowed a greater extent of movement than is said component, a bow spring extending between said movable fulcrum means and said movable component and having its ends fulcrumed respectively on said movable fulcrum means and said movable component, 10 a compression spring extending between said fixed fulcrum means and said movable component, said compression spring having its ends fulcrumed respectively on said fixed fulcrum means and said movable component and being held in compression throughout the travel of said movable component between said positions, and operating means operatively connected to said movable fulcrum means to move the same, said bow spring being effective to move said component and said controlling means with a snap action from one of said positions to the other in response to movement of said movable fulcrum means, and said compression spring being effective to bias said movable component to either of said positions.

7. In a snap action device, the combination of a movable component to be snapped from one operative position to a second operative position and thence back to said first position, controlling means carried by said movable component; spaced stop means disposed for engagement by said component in said positions, a pair of bow springs aligned across said component and extending laterally of the path of travel thereof, the adjacent ends of said springs being fulcrumed on said component, means spaced laterally of said path of travel and presenting a fixed fulcrum portion centered between said operative positions of said component, the other end of one of said springs being fulcrumed on said fixed fulcrum portion, said one spring being eifective to bias said component with a resilient force tending to maintain the same in either of its operative positions, a pivoted member having its free end disposed for movement generally in the direction of travel of said component and spaced therefrom, the other end of the other of said springs being fulcrumed on said free end, second spaced stop means operatively associated with said pivoted member and centered on said fixed fulcrum portion to limit the movement of said free end, the spacing of said second step means being sufficiently great to allow said free end a greater extent of movement than is allowed said component by said first-mentioned stop means, said other spring being efiective to snap said component and said controlling means from one operative position to the other as said free end is pivoted past said fixed fulcrum portion, and means operatively associated with said pivoted member to pivot the same in either direction.

References Cited in the file of this patent 

